This invention relates to a method for purification of crude urokinase. More particularly, it relates to a method of preparing urokinase of high potency free of pyrogens.
Urokinase is a protein which is found in human urine in trace amounts. It stimulates the production in the blood of the clot-dissolving proteolytic enzyme, plasmin, and is useful in the treatment of certain circulatory disorders such as those which tend to cause the formation of blood clots in the cardiovascular or peripheral vascular systems.
Urokinase has been obtained from human urine by adsorption thereof on silica gel, activated diatomaceous earth, glass bead, aluminum magnesium silicate and so forth. However, urokinase obtained by such treatment is not satisfactory for the medicinal use because it still contains impurities such as pyrogens and clot-promoting substances (e.g., thromboplastin). In this connection, various methods for purification or urokinase have been known. For example, U.S. Pat. Nos. 3,256,158 and 3,957,582 disclose that purification of urokinase may be performed by contacting an aqueous solution of crude urokinase with a cross-linked dextran or a cross-linked diethylaminoethyl-dextran to have urokinase adsorbed thereon, eluting the adsorbed urokinase with a phosphate buffer solution from said dextran, and then recovering urokinase from the eluate. It has also been known that crude urokinase is purified by treating an aqueous solution thereof with Amberlite IRC-50, DEAE-cellulose, Sephadex G-50 and so forth.